This application pertains to the art of diagnostic imaging and more particularly to three-dimensional imaging.
The invention is particularly applicable to CT scanners and will be described with particular reference thereto although it will be appreciated that the invention has broader application such as generating three-dimensional diagnostic images from data acquired by magnetic resonance imaging.
With the advent of computed tomography ("CT") and magnetic resonance imaging ("MRI"), cross-sectional images of the human anatomy may be generated. Data obtained by the CT or MRI scanners is assembled and a gray scale is assigned in accordance with data obtained from a particular section of the data.
As organs are, however, three-dimensional in reality, a series of slices or scans must be taken, and a mental integration is required to visualize the actual anatomy. A need was presented to place such a series of reconstructed planar images in a more familiar format. This type of image reformation aids physicians in their mental integration. It also aids in filling the communication gap between radiologists, referring physicians, collaborators, and their patients. Better planning in medical treatments or surgical operations is resultant from this type of imaging.
In the last decade, there have been many suggested methods to reformat cross-sectional images and present them as a three-dimensional image from any perspective view. Essentially, five different approaches have been tried. These include the cuberille approach, the octree approach, the ray tracing approach, the triangulation approach, and the contour approach. Each of these approaches, however, suffers from its own distinct disadvantageous.
In order for a three-dimensional imaging processor to become practically useful, a system response must be extremely fast, ideally less than one second per frame if not real time. In the prior art systems, implementation at such speeds could only be achieved with use of special purpose hardware Such special purpose hardware is extremely expensive, and is generally not cost effective. Such dedicated hardware is not usable for other process operations except for its particular three-dimensional reformatting.
Another disadvantage of the prior art lies particularly with the cuberille-type approach. In such systems, preprocessing of original image data is required as the underlying model of this approach assumes that the three-dimensional object is composed of cubes of the same size. Since, in fact, input data from a CT or MRI scanner is typically not cubic as the distance between two consecutive slices is commonly much larger than the slice of pixels or reconstructed images, resolution and accuracy is forfeited.
The present invention contemplates a new and improved method and apparatus which overcomes all of the above referred problems and others, and provides a system for generating three-dimensional diagnostic images which is simple, economical, and readily adaptable to general purpose processor means.